Looks nice! Could be easily transformed into a NAS or a cheap IP camera or into a data collecting station. I just found about it on LinuxDevices, got the URL from two of my friends and now also here :-)

The performance should be broadly similar however I can't be sure because I can't work out what ARM architecture the Sheeva is meant to be based on. Let's assume ARM9 or ARM11 - this is an out-of-order core, then, so it may get the snip on the Cortex-A8 (the doubled power consumption seems to support that).

The i.MX515 (and Qualcomm's SnapDragon if you need another example) have built-in video though and quite possibly far better video decoders (and encoders, the Kirkwood diagram here seems to state MPEG_TS and audio which isn't too descriptive) so you may put the Sheeva processor definitely in the realms of communications and storage application area, and not the mobile entertainment area the i.MX515 (and SnapDragon) take on.

The fact that there are so many ARM chips out with roughly the same applications and roughly the same featuresets really makes me wish PowerPC was pushed harder. Freescale and IBM and AMCC had a hold on a market with strict licensing that meant they were the only people to go to for a certain class of processor (this is exemplified in the game console market where PowerPC is dominating, although Nintendo do have an ARM7 core in the southbridge).

Now if they all use ARM chips, any one of the competitors in the "ARM(s) Race" could supplant any other in any device at any time. Would you trade off millions of units sold for the risk that you would lose that customer after those millions of units? (this is exemplified by the iPod which has gone through double digit revisions and generations, nearly every one using some other chip - PortalPlayer probably though they had a sweet deal with the iPod Gen 1-4 but then Apple picked Samsung and Broadcom instead)